1. Field of the Invention
The present invention generally relates to a circuit protection device for interrupting overcurrents that occur due to surges, sparks, or the like.
2. Description of the Related Art
In recent years, various kinds of information services including the Internet have rapidly come into wide use. The construction of information communication networks has been greatly expedited, so that many devices, such as telephone sets, modem devices, and network devices, are complicatedly connected to one another through communication lines and commercial power lines. Thus, accidents may occur as follows. For example, a failure of the communication device can be caused by an overcurrent resulting from a lightning surge, which passes from the communication line to the power line or vice versa. Further, another failure of the communication device can be caused by a spark generated when a certain wire, which is cut for some reason, is brought into contact with an adjacent wire.
A fusible member (namely, a fuse), a mechanical switch, an electronic switch, or the like is used as a circuit protection device for opening a circuit when an overcurrent flows through a communication device. Generally, for instance, a circuit protection device employing a relay as a mechanical switch further has a circuit for detecting a current flowing through the communication line or the power line at all times, and a circuit for opening the relay when detecting an overcurrent.
A circuit protection device employing a fusible member requires replacement of the fusible member with a new one each time an interrupting operation is performed.
Further, a circuit protection device employing a mechanical switch, such as a relay switch, is large in size and weight, and unsuitable for protecting a very small and light circuit. Moreover, this circuit protection device employing a mechanical switch is slow in response, and cannot sufficiently protect the circuit.
Furthermore, a circuit protection device employing an electronic switch is complex in configuration.
Accordingly, in view of above-mentioned problem, an object of the present invention is to provide a repeatedly usable circuit protection device which is small in size, light weight, high in operating speed and simple in structure.
To achieve the foregoing object, according to the present invention, there is provided a circuit protection device that comprises at least one set of reed members having a pair of reed members, wherein each of the reed members is constituted of a magnetic material and disposed in such a way as to be opposed to the other of the reed members and has an end disposed in such a manner as to be apart by a predetermined gap from and contactable with an end of the other of said reed members, a magnetic-field generating unit placed in vicinity of the reed members set and adapted to generate a holding magnetic field, for maintaining a state in which the end of the reed members are in contact with each other, after the ends of the reed members are attracted to each other, and the contacts are closed, and a contact gap reduction unit for reducing the gap to a gap corresponding to a pull-in of the magnetic field generated by said magnetic-field generating unit.
The present invention provides such a circuit protection device for protecting a circuit against an overcurrent, which has a simple structure and is small in size and weight. The operating speed of this circuit protection device is high. Moreover, this circuit protection device is easily reset even after an interrupting operation is once performed on the circuit so as to interrupt overcurrent conditions. Thus, this circuit protection device can withstand repetitive use.